Intermediate ocean circulation and cryosphere dynamics in the northeast Atlantic during Heinrich Stadials: benthic foraminiferal assemblage response

Date 2022-05
Author(s) Depuydt PaulineORCID1, Mojtahid MeryemORCID1, Barras ChristineORCID1, Bouhdayad Fatima Zohra1, 2, Toucanne SamuelORCID3
Affiliation(s) 1 : Univ Angers, Nantes Université, Le Mans Université, CNRS, UMR 6112, Laboratoire de Planétologie et Géosciences, F-49000 Angers, France
2 : Institute of Geology and Mineralogy, Faculty of Mathematics and Natural Sciences, University of Cologne, Cologne, Germany
3 : Univ Brest, CNRS, Ifremer, Geo-Ocean, F-29280 Plouzane, France
DOI 10.17882/88029
Publisher SEANOE
Keyword(s) Intermediate water masses, AMOC, European Ice Sheet, Glacial Eastern Boundary Current (GEBC), Channel River, Benthic Foraminifera

The interaction between ocean circulation and ice-sheet dynamics plays a key role in the Quaternary climate. Compared to the surface and deep compartments of the Atlantic Meridional Overturning Circulation (AMOC), the study of intermediate depths during key time periods, such as Heinrich Stadials (HSs), remains poorly documented, especially in the Northeast Atlantic. Here we use benthic foraminiferal assemblage data to trace paleoenvironmental changes from ~32 to 14 ka cal BP at ~1000 m depth in the Bay of Biscay. Our results highlight the high sensitivity of benthic foraminifera, with species-specific responses, to continental (European Ice Sheet dynamics) and marine (AMOC) forcing factors during the last three HSs. In general, HSs were characterized by the concomitant presence of meso-oligotrophic and anoxia indicator species and the low abundance of high-energy indicator species. This confirms an overall sluggish intermediate circulation during the three HSs in the Northeast Atlantic. HS1 is distinctive by the abundance of high-organic flux indicator species during its early phase. This is consistent with the fact that HS1 was, by far, the most important period of ice-sheet retreat and meltwater release to the ocean over the studied time interval. Finally, foraminifera depict the mid-HS2 re-ventilation event due to regional glacier instabilities.

Licence CC-BY
Acknowledgements The production of this dataset and associated publication was funded by the CNRS-INSU-LEFE-IMAGO program (STING project), the ARTEMIS 14C AMS French INSU project, and the Region Pays de Loire programs (New Research Group initiative and Rising Star project TANDEM). S.T. was funded by French National Research Agency (ANR) via the LabexMER program (ANR-10-LABX-19-01) and the PIA TANDEM project (ANR-11-RSNR-00023-01). Salary and research support for the PhD student (First author) were provided by the French Ministry of Higher Education and Research. We thank Sandrine Le Houedec for core subsampling. Finally, the authors warmly acknowledge J.-F. Bourillet, P.I. of the BOBGEO cruise (, for his strong support on this research project.
File Size Format Processing Access
Foraminifera raw data of core BOBGEO-CS05 61 KB XLS, XLSX Raw data Open access
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Depuydt Pauline, Mojtahid Meryem, Barras Christine, Bouhdayad Fatima Zohra, Toucanne Samuel (2022). Intermediate ocean circulation and cryosphere dynamics in the northeast Atlantic during Heinrich Stadials: benthic foraminiferal assemblage response. SEANOE.